1000+ Head-Fier

I agree the tips sound great but they are just too hard for me. Ended up using Sony Hybrids on the ZSN, but upon tip rolling the BQ3 I found a tip that was the exact same mold as the stock ZSN tips but with a softer more gummy material very much like the JVC Spiral Dots. That's what I have on them now. I have no idea where it came from.
I tried them on the C10 when I got them, but didn't work out well. Ended up using Spiral Dots on the C10's

Formerly known as slaterlovesspam

I agree the tips sound great but they are just too hard for me. Ended up using Sony Hybrids on the ZSN, but upon tip rolling the BQ3 I found a tip that was the exact same mold as the stock ZSN tips but with a softer more gummy material very much like the JVC Spiral Dots. That's what I have on them now. I have no idea where it came from.
I tried them on the C10 when I got them, but didn't work out well. Ended up using Spiral Dots on the C10's

100+ Head-Fier

After comparison between ZS7 and c10
My conclusion is : They are very very closed.
- Same sensibility
- Same signature
- Same soundstage
- Same detail

But the difference are very very light
- ZS7 have slightly more mid bass
- C10 have slightly more sub bass
- C10 are slightly more aerial
- ZS7 have slightly more impact/punch
- ZS7 have slightly more high mid
- C10 are slightly, very very slightly more brilliant

They are very similar. I can use one zs7 in one side and c10 in other. The difference is to light for my ears and brain to feel a real difference. except for the bass. Few music with a lot of bass we can feel the difference

To resume the choice
C10 : more aerial, more brilliant, more sub bass
Zs7 : more punch, more mid bass, more warm

They are so closer with so difference in hardware. It's really impressive

I'll continue with cca c10 and zs10 and m6

M6 and c10 are similar too. But the M6 is better ( with silver filter ). More warm, more soft, voice have more body. Less bass and less impact. C10 are more bright but mid bass is less present. We can feel the big difference in Can you feel my heart - Bring me the horizon : 1:33.

Please consider that ZS6 was measured time ago, with another calibration, other cable and tips. This affects above 12kHz frequencies mainly.
These ZS6 were measured with sub-bass hole tapped (more sub-bass).
More upper mids in ZS7, mids are similar. ZS7's 8kHz peak is identical to ZS6's (expect similar or even a bit more sibilance). The big highs ~10kHz peak of ZS6 has turned into a big dip.

Using amplifiers with high output impedance

Used serial resistors (20Ω and 70Ω) to make the simulation. They added some distortion at lows.
The effect on highs is not big. If you plan to decrease sibilance, try foam tips (measurements in the future..); they'll have more influence on 8kHz peak.

cheers =))

NOTES
The crossover at 800Hz (transition from dynamic driver to mids balanced armatures) could be better; check distortion at that point in both sides.

100+ Head-Fier

IF.......the ZS7 is a BA10 with a lower frequency dynamic then that would explain why the ZS7 is getting so much love. The BA10's rich midrange is an incremental improvement of the ZS6's slightly thinner midrange. IMHO, if the ZS7 eschews the ZS6's 10-12khz lift in the treble (which is not an issue for me) but does inherit the ZS6's more visceral bass and soundstage depth...and if the ZS7 has the BA10's more balanced presentation then the ZS7 would certainly have an incredible price to performance ratio at $35+/-.

Click to expand...

Doc, it seems to me that you're describing the CCA C10 here, only that it doesn't quite have that mid-bass slam the ZS6 has. It's bass resolution and precision is superior to that of the ZS6, however. I don't have the ZS7.

100+ Head-Fier

EDIT:
NOTES
The crossover at 800Hz (transition from dynamic driver to mids balanced armatures) could be better; check distortion at that point in both sides.

Click to expand...

Hakuzen, thanks for your efforts! Really appreciated, as I used your measurements and graphs together with your recommendations to get the proper ear tips for my red ZS6 (medium-to-wide bore ball-shaped foams). They were perfect and made the ZS6 my favorite and best in-ears, even with the arrival of the ZSN. The CCA C10 now occupies that position.

Headphoneus Supremus

After comparison between ZS7 and c10
My conclusion is : They are very very closed.
- Same sensibility
- Same signature
- Same soundstage
- Same detail

But the difference are very very light
- ZS7 have slightly more mid bass
- C10 have slightly more sub bass
- C10 are slightly more aerial
- ZS7 have slightly more impact/punch
- ZS7 have slightly more high mid
- C10 are slightly, very very slightly more brilliant

They are very similar. I can use one zs7 in one side and c10 in other. The difference is to light for my ears and brain to feel a real difference. except for the bass. Few music with a lot of bass we can feel the difference

To resume the choice
C10 : more aerial, more brilliant, more sub bass
Zs7 : more punch, more mid bass, more warm

They are so closer with so difference in hardware. It's really impressive

I'll continue with cca c10 and zs10 and m6

M6 and c10 are similar too. But the M6 is better ( with silver filter ). More warm, more soft, voice have more body. Less bass and less impact. C10 are more bright but mid bass is less present. We can feel the big difference in Can you feel my heart - Bring me the horizon : 1:33.

100+ Head-Fier

I've a confession. I didn't really shelve the CCA C10 when it arrived. The temptation to hear more was so irresistible that it’s a wonder I even considered putting it aside for a while. I was so taken with the similarity to the KZ ZSN that I started listening to it and hasn't stopped since.

This similarity with the KZ ZSN not just in appearance but more importantly in sound particularly on first listen, surely must have caught the attention of those who have it. It is on this basis, using the ZSN as point of reference that I made my notes and hereunder present my impressions.

Introduction

CCA (Clear Concept Audio) has been heretofore established as a sister company of KZ (Knowledge Zenith), thanks to 1clearhead’s piqued curiosity and efforts. Its initial release was the CCA C04, a 1 DD (8 mm) + 1 BA (30095) hybrid that, as is increasingly common these days, was just one among many monthly—or weekly—releases by the multitudes of Chinese companies that are into the design, manufacture and sales of portable audio gear, including headphones. A drop of rain into the sea, so to speak. Naturally, the C04 generally passed under the radar of Chinese-made IEM enthusiasts although it did manage that blip on the screen as to make a number respond.

Now we have the CCA C10, another hybrid pair of in-ear monitors consisting of 1 10mm dynamic and 4 balanced armature (2 mid-frequency #50060 + 2 high-frequency #30095) drivers per side. Being a multiple-BA hybrid it admittedly triggered some flags at its relatively low price but mainly it caught attention (probably prompting numerous double-takes) because it looks so much like the KZ ZSN, a hybrid configured like the C04, but whose tuning and out-of-the-norm (for KZ) premium build and cable at its astounding $10-$15 price makes it very popular.

For some, chance may have played a major role in the creation of the ZSN, but I like to believe that for KZ—and for CCA—it’s more of an analogue of natural selection, at the level of viruses. I do not intend any pejorative connotation but that is how KZ has managed to remain afloat and survive and flourish, and progress in an astonishingly short period of time; by the continuous release, oftentimes concurrent, of so many different models of earphones as to flood the market. The templates and characteristics of those that sound good, or more accurately, sell because they are perceived by a majority of enthusiasts as sounding good, are retained and adapted in a new iteration in each succeeding generation, using increasingly better resources with correspondingly better techniques, done by original research or otherwise copied, and each time there is an incremental improvement. Sometimes, this improvement is huge.

Clearly serendipity and/or evolution also favors the CCA C10.

Build, Fit, Comfort, etc.
The C10's cable is similar to the one that came with the KZ AS06 but with the metal earpiece connectors found in the KZ SPC flat-braided replacement cable. Its plug is also L-shaped. It is however loosely braided and not as soft, thus annoyingly prone to tangling.

As I’ve previously posted, the preformed ear guide leading to the right connector of the stock CCA C10 cable arrived bent out of shape so I tried a fix but the implement to fix it broke. So I changed cables, using a spare KZ SPC cable above-mentioned. It made no audible difference that I could discern.

At first glance or from a cursory examination it would seem that the C10 shell is identical to that of the ZSN.

Not quite.

Both the C10 and ZSN have metal faceplates (as per product details, zinc alloy for the C10 while aviation aluminum alloy for the ZSN) covering the main resin shells but that of the latter is screwed on while the former's obviously snaps into place.

Yes, both shells may have the same shape and general dimensions, but the C10 nozzle is stubbier and is an extension of its resin shell. The ZSN nozzle is longer and made of metal. Both have nozzle openings of the same diameter, but the C10 nozzle is a straight tube all the way to where it flares to follow the contours of the shell. The ZSN nozzle has a collared rim, approximately a millimeter in thickness and about half that in depth such that from this flanged opening the nozzle tube is smaller by at least a millimeter compared to that of the C10 until the flared base. The projection angle of the ZSN nozzle relative to its axis that's perpendicular to its faceplate is more obtuse than that of the C10.

Therefore with the ZSN you have this latitude where ear tips are concerned: changing them is so much easier; they most likely would remain in place when the earphones are removed; and most replacement tips being sold could possibly fit.

Note: I don't have side-by-side close-up pictures between the C10 and the ZSN to show off nozzle differences because the one foam tip I have that’s perfect for the C10 is stuck on its nozzle and I dare not attempt removal until the tips I ordered arrive. Sorry. Others have posted side-by-side pics sans tips, though.

On the other hand the C10 would need ear tips with a comparatively larger core or inner tube diameter. Unlike with the ZSN where the fit seems bespoke to my ears I had a problem getting a secure fit and seal using my available eartips with the C10. Even with an ideal fit courtesy of foam tips (below) the shorter nozzle and its somewhat more vertical orientation result in a rather shallow insertion and an ever so vaguely awkward feeling. For sure, it's not as vanish-in-your-ears comfortable as the ZSN. In the course of 5 or so days I have adjusted and have become accustomed to this niggle so now I could listen for hours without being bothered by it.

Using my favorite wide-bore soft silicone tips, I hear anemic bass and I have to push the shell a bit downwards and further inwards from the top where it rests against the antihelix to get the desired bass fullness. I found a pair of medium-size medium-to-wide bore ball-shaped foam tips in one of the KZ boxes so I changed ear tips. The contrast in bass response was like dusk and noon, yet there seemed to be no concomitant loosening of the bass nor did it become muddy or congested as is generally expected with generic foams. Resolution in the middle all the way up to the higher ranges is not affected as well, and there is that welcome attenuation of external ambient noise. I could posit that perhaps this is because the soft foam surrounding the tip opening are pushed back as they're inserted, the bigger nozzles creating a tighter passage, thus fully exposing the nozzle at the same time completely plugging the cavity between the nozzle and the ear canal.

I must mention that when I first attempted to insert the C10 into my ears with its pre-attached small-bore silicone tips there was considerable driver flex in both ear pieces. Very carefully inserting each in-ear one after the other by first pulling the helix of the ear upward and back to straighten the ear canal, slightly angling the tip forward and towards the top of my head, then with my mouth open moving the earpiece around, minimized the crinkly crackly sounds but did not eliminate them altogether. It seems the foam ear tips I'm currently using are more effective towards this end because I rarely encounter driver flex now.

As regards build quality the C10 earpiece is okay, but it doesn't seem to have that premium ZSN feel. With regard to ergonomics and design forethought it and its cable are to me a distressing retrogression to earlier KZ models. Yet in light of all this I'm still shaking my head in wonder at how KZ has managed to produce the ZSN, getting so many things right in the process—including the most important aspect of sound, and yet retail it at an amazingly low price. Plainly the ZSN is a budget IEM champ. As for the C10, sound is where its metier lies.

Sound

In their respective product details in AliExpress, the dynamic driver of the C10 is stated as a “10mm double magnetic circuit dynamic unit” which is a “low distortion professional dynamic unit” with “magnet volume increased by 30%” while that of the ZSN is a “10mm self-developed titanium film dynamic unit” that brings “stronger driving force with a four-layer voice coil”. This may be true and the two dynamic drivers may in fact be different, or they may after all be identical, because the C10 and ZSN bass do share similar characteristics.

C10 bass is tight, punchy, as fast and as controlled and reaches as deep into the sub-bass as that of the ZSN. Perhaps even deeper. It also seems to have more mid-bass prominence which imbues a warmer foundation to the C10’s sonic signature. The transition from upper bass into the lower mid-range is more restrained; I encountered masking of mid-range details only in the most complex songs. Because of this I could say that the C10 resolves low frequency textures and details a bit more. In my swinging and bebop Jazz reference tracks where the double bass and the drums exclusively set the underpinnings of the rhythm, I could, in the C10, just begin to discern the delineation between the percussive impact of the kick drum and the snap of the bass strings when plucked, as well as the trailing edges of these transients, from the faster decay of the drum to the slower and lingering reverberation of the double bass. In the ZSN I could not; these details seem to be there yet not there, inchoate, blending together in the field of sound being reproduced. I can only imagine what it would be like to listen to a pair of TOTL IEMs with all such gradations of textures and dynamic progressions of transients presented with all accuracy, precision and clarity. Still I cannot help but marvel at the resemblance between the two in-ears in the way they reproduce bass.

Like the ZSN, the C10 does not sound as recessed in the mid-range relative to the rest of the frequency spectrum but, unlike with the ZSN, the sensation of proximity is not as pronounced. Voices, both male and female, aside from having more body are not presented as upfront (or more precisely, in-your-ears) as in the ZSN. This sets up a broader sense of perspective where the voice is not disembodied as it sometimes is with the ZSN in close-mike vocal recordings; but is perceived as a resultant of movement of air from the chest, through the larynx and throat, shaped by, and out the mouth and nostrils. Female voices are especially intoxicating in the C10, such that I'm totally engaged in the absolute mastery of restraint and vocal control of Sarah Vaughan and Barbra Streisand, the perfect pitch and effortless technique of Ella Fitzgerald, the raw emotion evoked by Billie Holiday's phrasing and tempo.

Instruments too seem more natural with the C10; drums, cymbals and their iterations, strings, winds and the piano just sound more lifelike. Or perhaps it's because the warm foundation of the bass imparts fullness, a sense of solidity, which I very much like and prefer.

I also hear in the C10 the rudiments of that ability to resolve more subtle details across the audible frequency range that I fully enjoy with the HiFiMAN HE-400i and that I have never as completely heard from any of my other earphones, with the exception of my venerable detail champ, the Ostry KC06A: finger plucks on strings, fingers sliding and pressing on the finger board, ringing squeaks of finger pads on strings during that vibrato, the thumps of fingers on trumpet pistons and other such mechanical interaction with instruments; taxed breathing by cellists; sharply drawn huffs and more gentle puffs of air, those wet smacks as singers’ lips open and close. Again I imagine what it must be like to listen to such with IEMs that are the absolute best in detail and resolution. But to hear them, even on a basic level, from a $26 IEM ordered online for COD is truly liberating.

The C10 has no problem with vocal sibilance (S, T and Z and other fricative and affricate consonants generally heard from 4-5 KHz and sometimes to 8 or even 10 KHz). It must be noted that sibilance per se is part, and a natural function, of human speech. Every day we express, and hear, sibilant speech. Think “She sells seashells by the seashore.” It is only when vocal sibilance inherent in a recording is improperly or unnaturally reproduced as when there is harshness or stridency even at low to moderate volumes that it becomes irritating and undesirable.

Spanish Harlem sung by Rebecca Pidgeon from her album The Raven (Chesky, 1994) and the first song track in Chesky's Ultimate Demonstration Disc is an example of a naturally sibilant recording, what with all those sibilant consonants in the lyrics. The vocal sibilance is there, but it is integral to a song that's oftentimes used as a benchmark for high resolution audio. Attenuating or smoothing this will result in a corresponding loss of detail—for one, the distinctive variations in the sound of the shaker won’t be there anymore. If the headphone or speaker has a spike in the frequency range concerned, then Spanish Harlem would be intolerable. Therefore the reproduction of Rebecca Pidgeon’s voice has to be just right.

Another test for sibilance, a comprehensive one at that, is Linda Ronstadt’s trilogy of traditional American standards, also known as the “Round Midnight” trilogy: What’s New, Lush Life and For Sentimental Reasons. Ronstadt’s manner of singing and the way she articulates and aspirates her words in the languid style of these recordings naturally emphasize the sibilant consonants.

I’m very glad to say that the C10 aces both of the above.

Treble detail and clarity is likewise better expressed in the C10. Continuing with what seems to be its main character of restraint and control, it also exhibits that crispness and sparkle found in the ZSN but with a finer yet smoother silhouette. At first I perceived the upper brilliance region as somewhat subdued, with a limited sense of air up top, in direct comparison with the ZSN which seems to extend more. Later on I realized I mistook the ZSN’s intrinsic brightness as superior extension and airiness. Indeed, listening to Lush Life from Maynard Ferguson’s high-energy Live From San Francisco album (Omnivore, 1994) showed this. Ferguson’s acclaimed ability to play the trumpet in extremely high registers with full tone and power yet preserving musicality is showcased in this John Coltrane jazz standard. The C10 handled all of the soaring trumpet notes against the backdrop of the shimmering cymbals and the other horns with composed dexterity while with the ZSN I always have to turn down the volume a bit in certain passages because they are borderline strident. It seems the C10 presents detail with a restrained, smooth, glare-free transparency, if one could visualize the metaphors I’m using. I actually prefer this smoothness of treble character, conducive as it is to longer fatigue-free listening sessions.

Imaging, the positional and spatial cues in the sound field (e.g., where the musicians are situated, their distance relative to each other, and to the walls of the room in a live chamber music recording), is excellent in the C10. Going through the entire Ultimate Demonstration Disc and the Ultimate Headphone Demonstration Disc (both from Chesky Records) confirms this. The album Live From Studio A in New York City (Chesky, 1994) featuring Johnny Frigo with Bucky & John Pizzarelli, Ron Carter, Michael Moore and Butch Miles is a stellar model and audiophile standard for imaging (See Reference Notes). I appreciate listening to this with the HiFiMAN HE-400i, the imaging of which is for me perfect. The C10 out of all my earphones comes closest to that aural experience.

Soundstage, which determines the shape and size of the sound field that contains all those imaging cues, and that is created by the headphone itself, is very wide, with sufficient depth in the C10. The left and right expanse and receding extent of the horizontal sound field are easily perceived; height, however, takes focus to place. Admittedly all these are still taking place within the confines of my head, with the center image of sound still plastered to the upper middle of my forehead. The aforementioned Live From Studio A and binaural recordings such as Ottmar Liebert's Up Close (Spiral Subwave, 2008) and Stripped featuring Macy Gray (Chesky, 2016) heighten the illusion of an out-of-the-head sound image. If one has an app with a Crosstalk function like the Audioforge Equalizer for iOS devices, one could further enhance said illusion by creating a phantom center image that resides in front of and outside the head, thereby making the sound image more coherent with the absence of that hole in the middle. All my earphones have failed to recreate this illusory image except, to a certain extent, the ZS5 v1. I'm very happy that the C10 places a definite second to the ZS5v1 in its ability to reproduce at least a semblance of such illusion. I swear I could hear Macy Gray's raspy voice floating a couple of meters in front of my forehead for the first few syllables in Annabelle, the first track in Stripped. Likewise, Entrance + Tuning which is the last track in Up Close startled me because I thought someone had actually entered the room—notwithstanding the countless number of times I have listened to it.

Summary

As I went over my notes made in the course of listening to the CCA C10, it was immediately obvious that my impressions of its sound are all positive. Without any context (my limited experience with IEMs and the actual ones I have listened to) what I've written here might as well apply to a very capable high-end pair of in-ears. But CCA is, for all intents and purposes at this point in time, definitely not a high-end brand. And the C10 is a budget hybrid IEM that retails for approximately $30 US and which I bought for $26. As a matter of fact, with regard to build and design, cable, fit and comfort, and general feel, I find that it lags behind its KZ cousin—the ZSN, that I got for ~$10.78—to which it bears a striking resemblance not just in appearance but in base sound signature. And at present nobody would ever assert in any discussion, much less accept, that KZ is a high-end brand.

This head-scratching cross-dichotomy if you would, was brought to the fore when, in response to an earlier post of mine, I was asked whether my statement that the C10 is more or less double the price of the ZSN carries with it a positive or negative connotation. I haven't yet spent sufficient time with the C10 to give a straight answer then.

Now, I can: Notwithstanding whatever perplexing inferiority the C10 has to the ZSN in other aspects, in terms of pure sound quality alone I would take the C10 anytime.

Upon first audition the C10 sounded eerily similar to the ZSN—especially if one has just listened to the latter. Over time however the C10's refinement, technical prowess and ability to resolve more detail became manifest. It's simply more coherent, has that bit more natural tonality and timbre and has a more pleasant, warmer foundation than the ZSN. Technically it is on a higher level; its bass resonance, resolution, precision and control are just better, although there is a lack of weight in impact when compared to say, that of the Simgot EN700 Pro, or just even the KZ ZS6. Rendition of vocals, especially female is simply heady delicious. Its smooth, glare-free yet transparent presentation of treble makes for hours of fatigue-free enjoyment. And its handling of the dynamics of the music content makes it the most proficient among all my earphones, pitifully small in number they may be. Insofar as over-all sound reproduction is concerned I’d place the CCA C10 in the same level as my husband's Simgot EM1, a balanced, single DD with rich bass, a seductive mid-range and energetic presence region.

In short, the $26 C10 is my best so far, by far. Until the next sub-$30 wonder dethrones it. It could be the ZS7, if ever it falls under $30 in upcoming sales. Or it could be one which combines the tuning of the C10 with the shell and accessories of the ZSN, with those increscent improvements in internal structure and design—at the same price point, of course. As I’ve said here many times, my pleasures are simple.

Reference Notes
Comparative adjectives are used strictly within the context of how the C10 and ZSN compare to each other, unless otherwise specified.

These impressions were obtained listening to reference tracks through my usual gear setup (Cayin N3 low gain, Super Slow filter, EQ off, line out using FiiO L16 IC to Topping NX4 low gain, bass boost off) and using a medium-size medium-to-wide-bore ball-shaped foam eartip. Cable used is the Type A SPC KZ replacement cable with the silver-colored metal connectors and flat braid (the one that turns green).

Although I don't go through the usual initialization procedures, preferring to listen right away, the C10 did have an accidental slight burn-in when I left them connected to my Cayin N3-Topping NX4 combo that was still turned on and only discovered my inadvertence much later.

The sensitivity of the C10 is given in its product description as 108 dB, while that of the ZSN is given as 104 dB. I assume the unit is dB/mW. Both are specified to have an impedance of 32 Ohm.

Coming from 2-channel stereo, my perception and definition of “soundstage” has always been in that regard; i.e., what I could hear when seated at the sweet spot of 2 stereo loudspeakers properly toed in, and with the various interactions of the sound waves with the topology of my listening room.

Some albums (only certain tracks unless specified) used for reference, in no particular order:

Special Note: Chesky Records' "Live From Studio A in New York City" Featuring Johnny Frigo with Bucky and John Pizzarelli as Audiophile Reference

This is the album that launched Chesky Records, their very first, when it was released in July of 1994. It also launched the career of Johnny Frigo as one of the foremost exponents of swing jazz violin. It showcases the violin and guitar, with the double bass and drums forming the backdrop. It was recorded live in RCA's legendary Studio A in New York City in November 16, 1988, in order to capture all the clear, pure nuances of the two showcase acoustic instruments with Bob Katz (whose articles you may have come across in InnerFidelity during Tyll Hertsens’ time) as engineer.

In Bucky Pizzarelli’s words, “We used only one mike and no amplifiers. John, my son, and I used old guitars like the ones they used to use in big bands instead of the seven string guitars that we usually use now. We made the album in the old fashioned way. We sat around the mike—the five of us: Johnny Frigo, my son John, Michael Moore or Ron Carter on bass, Butch Miles on drums and me—and we just played. There was no splicing. No earphones. It put everybody on a sharp edge to get it done right.”

Live From Studio A represents that rare once-in-a-lifetime occurrence where the passion, the intellectual and musical integrity and the improvisational skill and mastery of all musicians cohere to produce a moment of pure artistic beauty. There is passion, energy, creativity, wit, humor and style. Moreover, the sound image and the acoustic space are so clearly defined that each musician can be precisely placed. To date, it remains one of the finest pressings Chesky ever made, and which I wholeheartedly and most highly recommend to everyone who loves music for them to appreciate and to test their system.

Disclaimer: I am not affiliated with Chesky Records. I have no contractual agreement to promote them. I do not earn any remuneration or emoluments from them.

One other thing: a year or so ago I could hear the 15KHz tone at the end of the Beatles' A Day In The Life (Sgt. Pepper's Lonely Hearts Club Band 50th Anniversary, 2017); now I couldn't.

Headphoneus Supremus

They are very similar. I can use one zs7 in one side and c10 in other. The difference is to light for my ears and brain to feel a real difference. except for the bass. Few music with a lot of bass we can feel the difference

Click to expand...

Haha was too afraid to try such things. The balancing act just trying to figure out if both sides of the same model are close enough to each other let alone a whole other pair. I usually play mono music for this or test tones. Shift to left to right in terms of concentration. Pure madness.
Hmm is the left side lower than the right, or is it my asymmetrical ears holes or brain halves.

when the iem stick out unequally out of my tragus, i push one even harder to equalize this, risking ear drum damage.